Recovery of sulphur



July 27, 1931. R. F. BACON ET AL RECOVERY OF SULPHUR Filed Oct. 18, 1934 2 Sheets-Sheet 1 INVENTORS Raymond/P506012 h l/er flab-022 BY Q.

ATTO R N EYS July '27, 1937. R. F. BACON ;ET AL RECOVERY OF SULPHUR Filed Oct. 18, 1934 2 Sheets-Sheet 2 n n 5 MM Rad mmw N a 5 w mM l M w L BY slum ATTORNEYS Patented July 27, 1937 P'i'ET Fries RECOVERY OF SULPHUR Raymond F. Bacon, Bronxville, N. Y., and Wilber Judson, Newgulf, Tex.

Application October 18, 1934, Serial No; 748,948

6 Claims.

This invention relates to the recovery of sulphur and has for an object the provision of an improved process and apparatus for recovering elemental sulphur from metal sulphide-bearing material. More particularly, the invention contemplates the provision of an improved process and apparatus for recovering elemental sulphur from pyrites.

The present invention contemplates the effective utilization of heat capable of being developed by reactions involved in or associated with the oxidation of pyrites for the recovery of the sulphur of the pyrites in elemental form. The method of the invention involves the oxidation of an iron sulphide product resulting from the distillation of pyrites under such conditions as to produce suflicient heat to facilitate the reduction of sulphur dioxide produced in the oxidizing operation and to eifect the distillation of the pyrites. 00 According to a preferred method of the invention, the iron sulphide residue from a pyrites distillation operation is subjected to an oxidizing treatment while molten to produce iron oxide and a gaseous product containing sulphur dioxide. According to another preferred method of the invention, the iron sulphide residue from a pyrites distillation operation is subjected to a suspension roasting operation to produce iron oxide and a gaseous product containing sulphur dioxide. The oxidizing operations are so controlled that the temperatures of the gaseous products are sufiiciently high to efiect a reaction between the sulphur dioxide contained therein and a reducing agent. The gaseous product of the oxidizing operation is passed in contact with a reducing agent to effect the reduction of the sulphur dioxide contained therein to elemental sulphur. Any suitable type of apparatus may be employed for carrying out the reducing operation. For example, the hot gases from the oxidizing operation may be passed in contact with a porous bed of coke in a suitable reaction chamber, or the gases may be passed through a rotary kiln in which a charge of coke is maintained.

The hot gaseous product of the reducing operation, containing elemental sulphur vapor, is passed in contact with finely divided pyrites in suspension to distill the volatile sulphur of the pyrites and to produce an iron sulphide product 50 which is subsequently treated in the oxidizing operation.

The invention will be better understood from a consideration of the following description in conjunction with the accompanying drawings showing schematically apparatus which may be employed in carrying out a process of the invention and in which Fig. 1 illustrates apparatus for use in carrying out the method of the invention when the residue from the distillation operation is subjected to the 5 action of an oxidizing gas while molten; and

Fig. 2 illustrates apparatus for use in carrying out the method of the invention when the residue from the distillation operation is subjected to the action of an oxidizing gas while in suspension in the oxidizing gas.

The apparatus shown in Fig. 1 of the drawings comprises an oxidizing chamber In in the form of a molten bath receptacle, a reducing furnace H, a heat exchanger I2, a distillation chamber i 3, a dust collector M, a condenser l5 and an electrical precipitator It, all so connected by means of suitable conduits that gases from the oxidizing chamber may be subjected successively to. reducing and heat exchanging treatments, utilized for distillation purposes, and subjected successively to dust removing, cooling or condensing and precipitating treatments.

The oxidizing chamber H] is similar in structure to an ordinary copper converter, and comprises a steel outer shell lined with refractory material such as magnesite brick. The upper portion of the oxidizing chamber communicates with a screw conveyor It which is adapted to deliver materials to be treated to the oxidizing chambers. The screw conveyor I6 is so constructed and arranged that materials may be delivered to the oxidizing chamber without admitting air. The lower portion of the oxidizing chamber is provided with a tapping spout ll through which the molten oxidized product may be withdrawn upon completion of the oxidizing treatment.

The upper portion of the oxidizing chamber is tightly connected to a conduit or flue l8. An annular manifold 20 surrounding the oxidizing chamber and communicating therewith through tuyeres 2i is provided for introducing air into the oxidizing chamber.

The oxidizing chamber may be stationary or mounted for tilting movement on any suitable type of supporting structure.

. The reducing furnace II is an upright cylindrical chamber lined throughout with heat refractory material and having a covering of heat insulating material. A grate 22 capable of supporting a porous bed of coke 23 is disposed between the top and bottom of the furnace. The lower portion of the furnace communicates with a screw conveyor 24 which is adapted to convey ash from the interior of the furnace to the discharge outlet 25. Coke may be introduced into the interior of the furnace above the grate from a storage hopper 26 through a pipe 21 having valves 28 and 38 therein. The valves 28 and 36 may be operated alternately to admit coke to the interior of the furnace without admitting air. The screw conveyor 24 is so constructed and arranged as to seal the furnace against the admission of air during the course of ash removal. An annular manifold 3i surrounds the lower portion of the furnace and communicates with the interior thereof below the grate 22 through the tuyres 32. The manifold 3| communicates with the conduit [8 leading from the oxidizing chamber. The conduit I8 is of such a length and in sulated in such a manner that gases may be delivered from the oxidizing chamber it to the reducing furnace ll without any substantial loss of heat. A gas outlet 33 disposed adjacent the top of. the reducing furnace communicates with the heat exchanger l2,

The heat exchanger I2 comprises an inner chamber 35 formed of good heat conducting material and a heat insulated jacket 36 surrounding the inner chamber and having its walls spaced from the walls of the inner chamber to provide a passage therebetween. The passage between the inner chamber 35 and the jacket 36 of the heat exchanger is provided with staggered bafiles 31 for providing a tortuous path of travel for gases. Air may be admitted to the passage between the inner chamber 35 and the jacket 36 through an inlet 38, and heated air may be withdrawn through a conduit 46 which communicates with the manifold 25 associated with the oxidizing chamber. phere or connected to a suitable source of air under pressure (not shown) communicates with the conduit it. A blower 12 is included in the conduit Ali to cause a iiow of air through the heat exchanger and to aid in introducing air into the oxidizing chamber.

A conduit d3 having a fan 44 included therein provides a passage for conducting gases from the interior of the inner chamber 35 of the heat exchanger to the distillation chamber Hi. The distillation chamber [3 is an upright cylindrical chamber similar in structure to the roasting chamber. The upper portion of the distillation chamber communicates with a screw conveyor .5 which is adapted to deliver materials for distillation from a storage hopper 45 to the distillation chamber. The lower portion of the distillation chamber communicates with the screw conveyor l6 which delivers materials to the oxidizing chamber. The screw conveyors 45 and iii are so constructed and arranged that materials may be delivered to and removed from the distillation chamber without admitting air. A grate 4! is disposed within the lower portion of the distillation chamber to collect agglomerations too large for convenient passage through the conveyor IS. A work hole 48 provided with a suitable removable cover permits access to the interior of the distillation chamber for the purpose of removing or breaking agglomerations collected on the grate 41. An annular manifold 55 surrounding the distillation chamber and communicating therewith through tuyres i is provided for introducing hot gases from the heat eX- changer 12 through the conduit 43 to the interior of the distillation chamber.

A conduit 52 provides a passage for conduct-- ing gases from the interior of the distillation An air inlet ll open to the atmos chamber to the interior of the dust collector M. The dust collector is provided with a series of baffles 53 so arranged as to provide a tortuous path for the flow of gases between the inlet conduit 52 and the outlet 54. The bottom of the dust collector is provided with a number of hoppers 55 for the reception of dust particles removed from the gas stream. The hoppers 55 are provided with valved outlets 55 through which dust particles collected in the hoppers may be withdrawn. The outlet 54 of the dust collector communicates with the upper portion of the condenser lb.

The condenser I5 is in the form of a fire tube boiler provided with a valved inlet 57 for water and a valved outlet% for steam. Condensate formed in the condenser may be withdrawn from the lower portion thereof through a valved outlet Eil. Gases may be withdrawn from the condenser through an outlet 5! having a fan 62 included therein and delivered to the electrical precipitator I9 which may be of any suitable construction.

The apparatus shown in Fig. 2 of the drawings comprises a suspension roasting chamber it, a dust collector ii, a reducing furnace 12, a distillation chamber 13, a dust collector i l, a condenser l5 and an electrical precipitator all so connected by means of suitable conduits that gases from the roasting chamber may be subjected to dust removing and reducing treatments, utilized for distillation purposes, and subjected successively to dust removing, cooling or condensing and precipitating treatments. The roasting chamber i6 is an upright cylindrical chamber covered with heat insulating material and provided with a heat refractory lining. The upper portion of the roasting chamber communicates with a screw conveyor is which is adapted to deliver materials to be roasted to the roasting chamber. The lower portion of the roasting chamber communicates with a screw conveyor ll which is adapted to convey solid materials from th roasting chamber to a discharge outlet it. The screw conveyors l6 and W are so constructed and arranged that materials may be delivered to and removed from the roasting chamber without admitting air. A grate 8B is disposed within the lower portion of the roasting chamber to collect agglomerations too large for convenient passage through the conveyor it. A work hole '86 provided with a suitable removable cover permits access to the interior of the roasting chamber for the purpose of removing or breaking agglomerates collected on the grate 86. An annular manifold 82 surrounding the roasting chamber and communicating with a fan 55 and with the interior of the roasting chamber through tuyeres 83 is provided for introducing air into the roasting chamber.

A conduit 84 provides a passage for conducting gases from the roasting chamber to the dust collector H. The dust collector T! is provided with a series of baffles 89 so arranged as to provide a tortuous path for the flow of gases between the inlet conduit 84 and an outlet conduit 85. The bottom of the dust collector H is provided with a number of hoppers 85 for the reception of dust particles removed from the gas stream. The hoppers 86 are provided with valved outlets 87 through which dust particles collected in the hoppers may be withdrawn. The outlet 85 of the dust collector communicates with the lower portion of the reducing furnace 12.

The reducing furnace I2 is an upright cylindrical chamber lined throughout with heat refractory material and having-a covering of heat insulating material. A grate 88 capable of supporting a porous bed of coke 90 is disposed between the top and bottom of the furnace. The lower portion of the furnace communicates with a screw conveyor 9! which is adapted to convey ash from the interior of the furnace to the discharge outlet 92. Coke may be introduced into the interior of the furnace above the grate from a storage hopper 93 through a pipe 9t having valves 95 and 95 therein. The valves 95 and 96 may be operated alternately to admit coke to the interior of the furnace without admitting air. The screw conveyor M is so constructed and arranged as to seal the furnace against the admission of air during the course of ash removal.

The outlet $35v of the dust collector ii conducts hot gases from the dust collector and the roasting chamber to the portion of the reducing furnace below the grate 88. The dust collector and the inlet and outlet conduits 84 and 35 are in-- sulated in such a manner that gases may be delivered from the roasting chamber to the reducing furnace without any substantial loss of heat. A conduit 97 having a fan 98 included therein communicates with the upper portion of the reducing furnace and the lower portion of the distillation chamber 13. The conduit 9"! is of such length and sufiiciently exposed that the gases from the reducing furnace will be below the temperature at which fusion or sintering of pyrites occurs when they reach the distillation chamber '53.

The distillation chamber 13 is an upright cylin drical chamber similar in structure to the roasting chamber. The upper portion of the distillation chamber communicates with a screw conveyor lfiii which is adapted to deliver materials for distillation from a storage hopper Hill to the distillation chamber. The lower portion of the distillation chamber communicates with a screw conveyor it??? which delivers materials to a grinding mill m3. Materials from the grinding mill are delivered to a hopper 99 and thence to the screw conveyor it in suitable form for suspension roasting. I-Ioods B5 and tit surround the feed and discharge ends of the grinding mill and prevent contact of the atmosphere with the material delivered to and discharged from the grinding mill. The screw conveyors Hill and tea are so constructed and arranged that materials may be delivered to and removed from the distillation chamber without admitting air. A grate tilt is disposed within the lower portion of the distillation chamber to collect agglomerations too large for convenient passage through the conveyor EH2. A work hole Hi5 provided with a suitable removable cover permits access to the interior of the distillation chamber for the purpose of removing or breaking agglomerations collected on the grate me. An annular manifold l 616 surrounding the distillation chamber and communicating therewith through tuyres till is provided for introducing hot gases from the conduit 91 to the interior of the distillation chamber.

A. conduit Hi8 provides a passage for conducting gases from the interior of the distillation chamber to the interior of the dust collector M. The dust collector M is similar to the dust collector ll, being provided with a series of baffles HE! so arranged as to provide a tortuous path for the flow of gases between the inlet conduit W8 and an outlet ML. The bottom of the dust collector M is provided with a number of hoppers l 2 for the reception of dust particles removed from the gas stream. The hoppers H27 are provided with valved outlets H3 through which dust particles collected in the hoppers may be withdrawn. The outlet Ill of the dust collector communicates with the upper portion of the condenser E5.

The condenser 75 is in the form of a fire tube boiler provided with a valved inlet l M for water and a valved outlet M5 for steam. Condensate formed in the condenser may be withdrawn from the lower portion thereof through a valved outlet H6. Gases may be withdrawn from the condenser through an outlet in having a fan H8 included therein and delivered to the electrical precipitator M which may be of any suitable construction.

In employing the apparatus illustrated in Fig. l of the drawings for carrying out a method of the invention, pyrites in finely divided form, preferably minus 40 mesh, is introduced into the upper portion of the distillation chamber l3 from the storage hopper it by means of the screw conveyor 15. The pyrites particles, in passing downwardly through the distillation chamber, encounter an upwardly rising current of hot gases introduced into the chamber from the heat exchanger l2 through the manifold 59 and tuyeres M. The heat contained in the gases functions to effect the distillation of the volatile sulphur of the pyrites, forming elemental sulphur vapor and a solid iron sulphide product. The solid iron sulphide product passes downwardly through the grate Al to the screw conveyor it which delivers it to the oxidizing chambcr lil. The iron sulphide-bearing material passes downwardly into a molten bath in the bottom of the oxidizing chamber.

Gperation of the oxidizing chamber may be initiated by melting a small charge of iron sulphide-bearing material in the chamber by com bustion of any suitable fuel or by retaining a portion of a molten bath produced in a preceding operation.

Air is introduced into the molten bath in the oxidizing chamber through the manifold 20 and tuyeres 2i. The oxygen of the air reacts with the iron sulphide to produce gaseous sulphur dioxide and molten iron oxide. The introduction of iron sulphide-bearing material into the oxidizing chamber may be continued for periods varying from one to several hours until the operating capacity of the chamber has been reached. When charging has been completed, blowing is continued until substantially all sulphur has been removed. The resulting molten bath, consisting largely of iron oxide is then removed through the tapping spout. A substantially oxygen-free gaseous product containing sulphur dioxide will be produced during the major portion of the blowing treatment. When the sulphur content of the molten charge is nearly exhausted the free oxygen content of the gaseous product tends to increase. The operation is preferably so conducted that the gaseous product delivered from the oxidizing chamber to the reducing furnace contains not more than about one percent of free oxygen. If desired, two or more oxidizing chambers may be employed in order to deliver sulphur dioxide to the reducing furnace continuously. When two or more oxidizing chambers are employed, they are operated in staggered relationship and means are provided for selectively connecting the oxidizing chambers in series and parallel, thus permitting the gaseous product from a chamber containing a molten charge substantially free of sulphur to be passed through a molten charge of higher sulphur content in another oxidizing chamber. By passing the gaseous product obtained in the treatment of a charge of relatively low sulphur content through a charge or bath of relatively high sulphur content, substantially all free oxygen contained in the gaseous product may be consumed and the continuous delivery of a substantially oxygen-free gaseous product to the reducing furnace may be insured. The sulphur dioxide, together with inert gases introduced into the roasting chamber with the air, passes through the conduit iii to the lower portion of the reducing furnace H.

The roasting operation is so conducted that the gases entering the reducing furnace have a temperature higher than about 1000 C. and preferably about 1209" C. or higher. The hot gases entering the lower portion of the reducing furnace pass upwardly through the porous bed of coke 23. The temperature of the gases is sufficiently high to maintain the coke in an incandescent state, and the carbon of the coke, therefore, reacts with the sulphur dioxide contained in the gases to effect its reduction and produce elemental sulphur. The gases containing elemental sulphur pass from the reducing chamber through the conduit 33 into the heat exchanger i2 and, during the course of their passage through the heat exchanger, the temperature is reduced by the transfer of heat to air drawn through the passage between the inner chamber 35 and the jacket 36. The air thus heated is introduced into the oxidizing chamber to aid in maintaining the desired temperature. Additional control of the temperature within the oxidizing chamber may be accomplished through the admission of varying amounts of cold air through the inlet 4i. The gases from the inner chamber 35 of the heat exchanger are delivered to the interior of the distillation chamber i3 through the conduit 33, manifold 59 and tuyeres 5i at a temperature of about 500 C. to 900 C.

Gases containing the volatile sulphur of the pyrites together with the elemental sulphur produced by the reduction of sulphur dioxide in the furnace H are withdrawn from the upper portion of the distillation chamber through the conduit 52 and delivered to the dust collector M. The sulphur laden gases pass through the dust collector to the outlet 5t and, during the course of their passage through the dust collector, substantially all dust particles are removed. The cleaned gases passing out of the dust collector through the conduit 54 enter the condenser IS in which a temperature sufficiently low to effect condensation of the sulphur vapor contained in the gases is maintained. A temperature of about C. to C. is preferably maintained in the condenser. Substantially sulphur free gases are conducted from the condenser through the conduit 64 to the electrical precipitator id in which entrained sulphur particles may be removed. Molten sulphur collected in the lower portion of the condenser is withdrawn through the outlet 6%.

In employing apparatus of the type illustrated in Fig. 2 of the drawings for carrying out a method of the invention, pyrites in finely divided form, preferably minus ill-mesh, is introduced into the upper portion of the distillation chamber 53 from the storage hopper lfil by means of the screw conveyor Hill. The pyrites particles, in

passing downwardly through the distillation chamber, encounter an upwardly rising current of hot gases introduced into the chamber from the conduit 97 through the manifold Hi6 and tuyres I07. functions to effect the distillation of the volatile sulphur of the pyrites, forming elemental sulphur vapor and a solid iron sulphide product. The solid iron sulphide product passes downwardly through the grate Hi4 to the screw conveyor 32 which delivers it to the grinding mill its in which the particles are reduced to sizes suitable for suspension roasting and delivered to the roasting chamber through the hopper 99 and the screw conveyor 16. The iron sulphide-bearing material is showered downwardly through the roasting chamber H3 and in passing downwardly through the roasting chamber the particles encounter an upwardly rising current of air introduced into the roasting chamber through the manifold 82 and tuyeres 83. The oxygen of the air reacts with the iron sulphide to produce gaseous sulphur dioxide and solid iron oxide. The solid iron oxide collects in the lower portion of the roasting chamber and is removed therefrom by means of the screw conveyor ii. The sulphur dioxide, together with inert gases introduced into the roasting chamber with the air, passes through the dust collector ii to the lower portion of the reducing furnace E2.

The roasting operation is so conducted that the resulting gaseous product is substantially free of oxygen and enters the reducing furnace at a temperature higher than about 1,000 C. and preferably about 1,206" C. or higher. The operation is preferably so conducted that the gaseous i product delivered from the roasting chamber to the reducing furnace contains not more than about one percent of free oxygen. The hot gases entering the lower portion of the reducing furnace pass upwardly through the porous bed of coke 9E. The temperature of the gases is sufficiently high to maintain the coke in an incandescent state,

and the carbon of the coke, therefore, reacts with the sulphur dioxide contained in the gases to effect its reduction and produce elemental sulphur. The gases containing elemental sulphur pass from the reducing chamber through the conduit 9Z manifold H16 and tuyeres it! into the interior of the distillation chamber.

Gases containing the volatile sulphur of the pyrites together with the elemental sulphur produced by the reduction of sulphur dioxide in the furnace "F2 are withdrawn from the upper portion of the distillation chamber through the conduit m8 and delivered to the dust collector "it. The sulphur laden gases pass through the dust collector to the outlet ii i and, during the course of their passage through the dust collector, substantially all dust particles are removed. The cleaned gases passing out of the dust collector through the conduit ii i enter the condenser '35 in which a temperature sufficiently low to effect condensation of the sulphur vapor contained in the gases is maintained- A temperature of about 115 C. to 150 C. is preferably maintained in the condenser. Substantially sulphur free gases are conducted from th'e condenser through the conduit H! to the electrical precipitator 54 in which entrained sulphur particles may be removed. Molten sulphur collected in the lower portion of the condenser is withdrawn through the outlet 1 55.

It is to be understood that the apparatus illustrated in the drawings is merely illustrative and is not intended to be restrictive of the invention'in any respect.

The heat contained in the gases.

We claim:

1. The method of producing elemental sulphur which comprises subjecting pyrites in a distillation chamber to a distillation operation in such manner that distillation of the volatile sulphur atom is effected and a product corresponding substantially to the moncsulphide of ironis produced, subjecting the resulting monosulphide in a suitable chamber to an oxidizing operation at a temperature substantially above 1,000 C. under such. conditions that a high-temperature gaseous product containing sulphur dioxide is formed, withdrawing said gaseous product from the oxiclizing chamber, passing the gaseous product after such withdrawal in contact with a bed of coke so as to reduce the sulphur dioxide and form a gaseous product containing elemental sulphur, and passing the gaseous product containing elemental sulphur in contact with pyrites in the distillation chamber in such manner that distillation of the volatile sulphur of the pyrites is effected.

2. The method of producing elemental sulphur which comprises subjecting pyrites in a distilla tion chamber to a distillation operation in such manner that distillation of the volatile sulphur atom is effected and a product corresponding substantially to the monosulphide of iron is produced, subjecting the resulting monosulphide in a suitable chamber to an oxidizing operation at a temperature substantially above 1,009 C. under such conditions that a high-temperature gaseous prod not containing sulphur dioxide is formed, withdrawing said gaseous product from the oxidizing chamber, passing the gaseous product after such withdrawal in contact with a bed of coke so as to reduce the sulphur dioxide and form a gaseous product containing elemental sulphur at a temperature of about 1,000 0., cooling the resulting gaseous product to a temperature of about 500 to 900 (3., and passing the resulting cooled gaseous product containing elemental sulphur in contact with pyrites in the distillation chamber in such manner that distillation of the volatile sulphur of the pyrites is effected.

3. The method of producing elemental sulphur which comprises subjecting pyrites in a suspension distillation chamber to a suspension distillation operation in such manner that distillation of the volatile sulphur atom is effected and a product corresponding substantially to the monosulphide of iron is produced, subjecting the resulting monosulphide in finely divided form to a suspension roasting operation at a temperature above 1,000 C. in a suitable chamber under such conditions that a high-temperature gaseous product containing sulphur dioxide is formed, withdrawing said gaseous product from the roasting chamber, passing the gaseous product after such withdrawal in contact with a bed of coke so as to reduce the sulphur dioxide and form a gaseous product containing elemental sulphur, and passing the gaseous product containing elemental sulphur in contact with pyrites in the distillation chamber in such manner that distillation of the volatile sulphur of the pyrites is effected.

4. The method of producing elemental sulph which comprises subjecting pyrites in a suspension distillation chamber to a suspension distillation operation in such manner that distillation of the volatile sulphur atom is effected and a product corresponding substantially to the monosulphite of iron is produced, subjecting the resulting monosulphide in finely divided form to a suspension roasting operation at a temperature substantially above 1000 C. under such conditions that a hightemperature gaseous product. containing sulphur dioxide is formed, withdrawing said gaseous product from the oxidizng chamber, passing the gaseous product after such withdrawal in contact with a bed of coke so as to reduce the sulphur dioxide and form a gaseous product containing elemental sulphur at a temperature of about 1000 C., cooling the gaseous product to a temperature of about 500 to 900 C. and passing the resulting cooled gaseous product containing elemental sulphur in contact with pyrites in the distillation chamber in such manner that distil lation of the volatile sulphur of the pyrites is effected.

5. The method of producing elemental sulphur which comprises subjecting pyrites in a distillation chamber to a distillation operation in such manner that distillation of the volatile sulphur atom is effected and a product corresponding substantially to the monosulphide of iron is produced, subjecting the resulting monosulphide in a suitable chamber to an oxidizing operation while in. the form of a molten bath at a temperature substantially above 1000 C. under such conditionsthat a high-temperature gaseous product containing sulphur dioxide is formed, withdrawing said gaseous product from the oxidizing chamber, passing the gaseous product after such withdrawal in contact with a bed of coke so as to reduce the sulphur dioxide and form a gaseous product containing elemental sulphur, and passing the gaseous product containing elemental sulphur in contact with pyrites in the distillation chamber in such manner that distillation of the volatile sulphur of the pyrites is effected.

6. The method of producing elemental sulphur which comprises subjected pyrites in a distillation chamber to a distillation operation in such manner that distillation of the volatile sulphur atom is effected and a product corresponding substantially to the monosulphide of iron is produced, subjecting the resulting monosulphide in a suitable chamber to an oxidizing operation while in the form of a molten bath at a temperature substantially above 1000 C. under such conditions that a high-temperature gaseous product containing sulphur dioxide is formed, withdrawing said gaseous product from the oxidizing chamber, passing the gaseous product after such withdrawal in contact with a bed of coke so as to reduce the sulphur dioxide and form a gaseous product containing elemental sulphur at a temperature of about 1000 C. cooling the gaseous product to a temperature of about 500 to 900 C., and passing the resulting cooled gaseous product containing elemental sulphur in contact with pyrites in the distillation chamber in such manner that distillation of the volatile sulphur of the pyrites is effected.

RAYMOND F. BACON. WILBER JUDSON. 

